1. Field of the Invention
This invention relates to a method of dry etching InAlAs as well as other Group III-V semiconductor compounds.
2. Brief Description of the Prior Art
In accordance with the prior art, Group III-V semiconductor compounds lattice matched to InP have generally been dry etched using a chlorine-based or methane and hydrogen plasma at about room temperature (about 34.degree. C.). While this etching procedure and composition has provided satisfactory results, it has not been capable of etching all semiconductor compositions of the Group III-V type which are lattice matched to InP at sufficiently high rates of speed, this being particularly apparent in the case of InAlAs. It is therefore evident that an etchant which is capable of etching InAlAs at etching rates comparable to the etching rates presently available for other Group III-V semiconductor compounds lattice matched to InP would be highly useful in the fabrication of such Group III-V semiconductor devices.
Niggebrugge et al. demonstrated reactive ion etching (RIE) of InP using methane and hydrogen. They observed that In reaction products have a low volatility and mentioned that CCl.sub.2 F.sub.2 /Ar/O.sub.2, Cl.sub.2 O.sub.2, SiCl.sub.4 and CCl.sub.4 /O.sub.2 have been previously used to etch InP. This is set forth in Institute of Physics Conference Series No. 79, Chapter 6, pp. 367-372, International Symposium on GaAs and Related Compounds, Karuizawa, Japan (1985).
I. Adesida et al. disclosed etching of InP, InGaAs and InAlAs using CH.sub.4 H.sub.2, CH.sub.4 /He and CH.sub.4 /Ar. They observed that the etching of InAlAs is predominantly through sputtering with etch rates under 150 Angstroms/minute at room temperature. This is set forth in GaAs and Related Compounds 1988, Institute of Physics Conference Series 96, pp. 425-429, 1989.
T. R. Hayes et al. has also reported on etching InP, InGaAs and InAlAs at room temperature using CH.sub.4 /H.sub.2. This is set forth in Journal of Vacuum Science Technology Bulletin, Vol. 8, No. 1, January/February 1990, pp. 57-67. The InAlAs etch rate was a maximum of 200 Angstroms/minute using C.sub.2 H.sub.6 /H.sub.2. They also reported etching InAlAs with CCl.sub.2 F.sub.2 /O.sub.2, but with a very poor surface morphology.